After the manufacturing of an implant such as a pacemaker or a defibrillator, and before its implantation the implant is usually stored. The typical energy consumption of a pacemaker held in storage is about 8 μA as opposed to about 12 to 22 μA after its implantation, depending on the programming and the degree of inhibition. It follows from these facts that two years of storage equal about one year of implantation. The energy consumed during the storage can, therefore, no longer be used during the implantation period so that the effective utilization time of the implant, i.e., the implantation time, is reduced.
The current “Use before” date, that is, the date by which the implant must be put in operation, depends on the date when the battery was connected, the date of sterilization, a product-specific time period, and it also takes into account the energy consumption during the storage. After the expiration of the “Use before” date, the devices that have not been implanted in the meantime are sent back to the manufacturer for a re-sterilization. In this process it can happen that such devices can no longer be delivered back as merchantable products due to the loss of charge during their storage. As a matter of fact, there is no substantial reason—except for the condition of the battery—that would enforce a maximum “Use before” period of, e.g., 24 months. The “Use before” time period could be extended by reducing the quantity of the current consumed during the storage, which could reduce the number of implants to be returned for re-sterilization as well as the number of implants to be scrapped.
The function of pacemakers and especially of defibrillators is dependent on the temperature. If during the storage or transportation the temperature is, e.g., below 5° C., there might occur mostly reversible but also irreversible defects. Units damaged in such a manner can usually no longer be supplied as normal products, since the current consumption after the defect and, therefore, the condition of the battery can no longer be determined with sufficient accuracy.
The current state of art knows electrical implants that are partially set into an energy-saving stand-by operation mode during their storage. In this process, certain components of the implant are usually disconnected, while other components continue to be supplied with current. The purpose of this energy-saving stand-by operation mode is to reduce the consumption of current during the storage.
U.S. Pat. No. 5,522,856 discloses an implant, which sets selected circuit elements of the implant into an energy-saving operation mode until the implant is implanted in a patient. This known implant further comprises a detector, which determines, whether the implant is being connected for the implantation. When such an implantation is detected, the circuit elements of the implant are switched into normal current-consuming operation mode. Furthermore, the implant can be removed from the storage, its function can be tested, and then the implant can be returned into the storage, where the implant is again switched into the energy-saving stand-by mode in order to reduce the current consumption during the storage. In addition, the implant can detect when the impedance at its electrodes is under a certain pre-set level. If this is the case, the implant remains permanently in normal operation mode.
U.S. Pat. No. 5,350,407 discloses an implant that can be put into a stand-by mode by means of an instruction from an external communication device, and can be put into an active mode by removing an activation pin, or by an activation instruction from external communication device. After the manufacturing of the implant an activation pin is introduced into the implant and the external communication device is triggered to transmit a deactivation instruction to the implant. In doing so, the energy supply to a section of the circuit components is disconnected, while energy supply is kept open to those circuit elements, which are required—in conjunction with the communication operation—to activate the remaining circuit elements. The implant is then activated either by the transmission of an activation instruction from an external communication device or by removing the activation pin.
As a consequence, the two aforementioned documents already disclose a reduction of current consumption of the implant during its storage. However, it is desirable to reduce the current consumption of the implant during its storage even more.
Therefore, the task of this invention is to further develop the design of an electrically active implant in such a manner as to further reduce the current consumption of the implant during its storage as compared to the current state of the art.